1. Field of the Invention
This invention relates to a rotary head-type recording or reproducing apparatus, and more particularly to apparatus of this type wherein a tape-shaped recording medium is supported on a pair of reels with an intervening loop of the medium formed and tensioned, and during loading of the medium, the loop is trained around a rotary head-equipped cylindrical member to permit the head to record signals on or reproduce signals from the medium.
2. Description of the Related Art
Discussion will now be had of a type of the above-noted recording or reproducing apparatus known as video tape recorders (VTRs).
FIG. 1 illustrates the general features of a VTR. A cassette 101 has a supply reel 102 and a take-up reel 103 contained within a housing. A magnetic tape 104 is convoluted on either or both of the reels 102 and 103. Before being introduced interiorly of the VTR, a portion 104 (shown by the dashed line in FIG. 1) of the tape within the cassette 101 and facing an open portion 101a thereof is in normal tension about a pair of guide pins 100a and 100b.
When the tape is introduced interiorly of the VTR, tape portion 104 is pulled out of the open portion 101a by means of moving guide posts 106, 107, 108 and 109 until its is trained around a cylinder 105 on the peripheral surface of which is a rotary head (not shown). The apparatus is accordingly readied for recording signals on or reproducing signals from the tape 104. At this time, the so-called "loading end" of the tape takes a disposition or path determined not only by the movable guide posts 106 to 109, but also by fixed guide posts 112, 113 and 114.
A loading ring 115 is supported so as to be rotatable along a guide member (not shown). Fixedly mounted on loading ring 115 are the movable guide posts 106, 107 and 108. A capstan 111 is pressed against a pinch roller 110 across the tape 104 when it is transported at normal speed along the aforesaid path. The pinch roller 110 is fixedly mounted on a lever 116 together with the movable guide post 109. In the course of loading, lever 116 is moved by a mechanism (not shown) from inside of the opening portion 101a to the position shown in FIG. 1.
In the described VTR, as the various modes, e.g., recording, reproducing, fast feed motion, cassette loading and tape setting, are selected and operated, each of the mechanisms experience state change. For example, the reels 102 and 103 change state between driving and braking. The capstan changes between driving state and idling state, i.e., in pressure against the pinch roller or not.
Although the selective setting of these modes can be effected freely by a user by pushing desired ones of operating keys, the coordination of all such mechanism need be controlled in a manner suited to the selected mode. For this purpose, the mechanisms may be provided with respective individual changeover members which are made electrically independent of one another to permit a system controller to control their operations. This method of coordination control is simple. But, the use of four or more electrical motors is required. One motor is needed for rotating the loading ring 115. A second is needed for driving the capstan 111. Third and fourth motors are needed for driving the two reels 102 and 103 independently of each other. Further, electrically operated plungers are required for bring the pinch roller 110 into pressing contact on the capstan 111 and braking pads into frictional contact with the respective reels. The employment of the described method involves a large size for the VTR. Besides the above-noted parts, there are many others which have to change their operative positions, as the VTR is switched from one mode to another. If mechanisms are provided for driving these parts and arranged to operate independently of one another and of the above-noted parts, the space they occupy is necessarily increased and production costs are increased.
Accordingly, the method of controlling the coordination of the above-noted variety of parts by means of electrically independent changeover members cannot be employed in VTRs wherein compact form and lightness in weight are of cardinal importance.
The most significant subject, in mechanical coordination control of the above-noted VTR components, is the accuracy of the changeover timing. In recent years, the art has seen the coordination control means constructed in the form of a lever with a layer number of camming surfaces and arranged to permit mechanical changing of the operative positions of the VTR components, depending on the selected mode, namely, control means hereinafter referred to as the "mode" lever.
In a VTR using the mode lever, a requisite is that the distances from the mode lever to all mechanisms to be coordinated be minimized. This implicitly requires that the mode lever should stand central to the multiplicity of such mechanisms. Further, an electric motor for driving the mode lever should be positioned adjacent the mode lever and known arrangements align the various mechanisms and their drive sources longitudinally of the mode lever with attendant difficulty in reducing the size of the VTR longtudinally of the mode lever.
Consideration may be given to a division of the mode lever into plural mode levers arranged to cooperate with each other with advantage in that the plurality of mechanisms are dispersed into cooperation with the respective plural mode levers. Because the two groups of the mechanisms are controlled by the respective plural mode levers, it becomes difficult to accurately control coordination between the diverse mechanism groups. The plural mode lever arrangement would detract from the significance of performance of the single mode lever arrangement.
Another consideration may be the non-use of a separate electric motor for driving the mode lever and the common use of a motor for driving both the mode lever and the loading ring 115.
However, for a common electric motor to drive the loading ring and the mode lever, demand arises for a mechanism for changing over the transmission of the driving torque of the motor between two paths and two latching mechanisms arranged to be selectively operated so that the one of the loading ring and the mode lever which is not to be driven is held stationary during the movement of the other, necessitating a complicated structure. Moreover, an additional mechanism is needed for controlling the operation such transmission changeover mechanism and selectively actuating the two latch mechanisms. Weight reduction of the VTR is accordingly not to be realized.
Another desire in the described VTR type of apparatus is to make the length and stroke of the mode lever as short as possible. However, where the mode lever is to be capable of bringing the pinch roller into pressure contact on the capstan, its stroke must be relatively long. In general, the fast tape-feed mode and the rewind mode are carried under the condition wherein the pinch roller is placed out of pressure contact with the capstan, while, in the record mode and the normal and various special reproduction modes, the applicable condition is that the pinch roller is pressed against the capstan in order that the capstan can regulate the speed of movement of the tape.
It has been difficult to reduce the stroke of the mode lever, since control coordination differs with different modes, and, since not only this difference, but the engagement and disengagement of the pinch roller are effected in the stroke of the mode lever. For this reason, in the conventional VTR, a limitation applies to the minimization of the length of the stroke of the mode lever.
As a cause of the such extension of the stroke of the mode lever, where the mode lever is used to change over the torque limiter between the engagement and disengagement dispositions, an idler driven by the capstan motor is removable from another idler which is drivingly connected to the reel through the torque limiter, and, after movement, is brought into engagement with still another idler, which is drivingly connected to the reel.
Another general feature of the VTRs of the character above is that the operation of the mode lever is performed during or after the tape loading. Even before the tape loading, however, there are many other mechanisms that change their operations.
For example, the ejection lever for the cassette holder is operated, and the reels in the cassette are released from the locking connection. Since, in the prior art, the operating mechanisms for these members were controlled by respective individual drive means, there is a limitation on reduction of the number of parts and of the size and weight of the apparatus.